1. Field of the Invention
The present invention relates to a semiconductor circuit, and particularly relates to a semiconductor circuit for detecting a signal propagation time.
2. Description of the Related Art
FIG. 2A shows a normal vector matching algorithm. In matching, how much an input pattern INP is similar to a template pattern TEM is detected. For example, the vertical axis of each of the input pattern, INP and the template pattern TEM shows a voice data value, and the horizontal axis thereof shows a time. In this normal vector matching, a difference DIF between the input pattern INP and the template pattern TEM is found with respect to each of corresponding horizontal axis values. The difference DIF is represented by an absolute value of a difference between both the patterns. It can be said that the smaller the difference DIF, the more similar the input pattern INP and the template pattern TEM are to each other.
On this occasion, in the input pattern INP, the number of data often increases or decreases somewhat with respect to the horizontal axis. In other words, data on some time axis is missing or data is inserted in some cases. Also in this case, a human being judges the degree of similarity by whether or not overall patterns of the input pattern INP and the template pattern TEM are similar to each other.
In this normal vector matching, however, if the number of data in the input pattern INP increases or decreases by even only one with respect to the horizontal axis, a correspondence between the horizontal axes of both the patterns cannot be obtained, and consequently the degree of similarity between both the patterns extremely reduces. Hence, an algorithm in FIG. 2B is devised.
FIG. 2B shows a DP (dynamic programming) matching algorithm. In DP matching, when the input pattern INP and the template pattern TEM are compared, a comparison is made without a correspondence between the horizontal axes being strictly regulated. Namely, the input pattern INP and the template pattern TEM are compared in a state where they are made movable in a horizontal axis direction. Consequently, the difference DIF between both the patterns reduces. In other words, even in the case where the difference DIF increases in the normal vector matching in FIG. 2A, the difference DIF reduces in the DP matching in FIG. 2B, which enables proper matching.
In DP matching, the input pattern INP and the template pattern TEM are compared in the state where the horizontal axes thereof are made movable, whereby there exist numerous comparison combinations. The difference DIF between the most similar combination among the comparison combinations is found. To realize this, many combinations need to be compared, which requires enormous processing time.